1. Field of the Invention
This invention relates to a printed circuit board.
2. Description of the Prior Art
Circuit boards are used in engineering to a great extent. They support on their upper and/or lower surfaces components for certain electrical circuits. Each circuit board is usually connected mechanically and electrically to other components. For this purpose, the circuit board supports almost always a connector adjacent to one of its edges. The connector generally has an insulating body, also called a housing, which is fastened to the circuit board. The insulating body is often screwed to the circuit board, the screws going through holes in the insulating body and holes in the circuit board aligned with the former. The contact elements in the insulating body are often connected in that the terminal ends of the contact elements are plugged into holes penetrating the circuit board, the conductive paths to be led out terminating at these holes. The terminating ends located in the holes are additionally soldered. It is also known already to have the terminal ends of the contact elements terminate near the circuit board surface so that the ends can be soldered to soldering points provided at the surface, these soldering points in turn forming the ends of the conductive paths to be led out.
In the surface mounted components technique also used nowadays, components are provided directly on the surface of a circuit board or printed circuit so that an insertion into predrilled holes is no longer necessary. Especially in circuit boards for this technique, no soldering holes for the accommodation of the terminal ends of the contact elements are provided any more so that the coordination between the connector connection and conductive paths depends upon the dimensional accuracy of the connector and of the circuit board. At the typical pitch dimensions of 1.27 mm this means that a slightly bent terminal end will lead to miscontacting. Another error source is the difference in the thermal expansion of the connector to be fastened and the circuit board during the soldering operation, i.e., when the terminal ends of the contact elements are to be soldered to the circuit board. The differing thermal expansions can cause the terminal ends or solder connections of the contact elements to not sit accurately on the associated terminal point on the circuit board any more.
In addition to the already discussed problems in connecting the contact elements electrically to the conductive paths, there is also the necessity of fastening the insulating body of the connector mechanically to the circuit board. This requires assembly holes, as already mentioned above. It would be extremely advantageous if the insulating body could be attached to the circuit board without the use of an assembly hole. This would be of particular advantage for the surface mount technique because it does away with soldering holes so that, if no assembly holes were required for the connector either, no holes at all would be needed in the circuit board.
It would be desirable to avoid the disadvantages of the state of the art, and in particular, to provide a circuit board equipped with a connector without requiring assembly holes in the circuit board and/or the connector. Also, it would be desirable to provide a precise connection of the contact elements of the connector to the conductive paths to be led out. Further, it would be desirable to avoid miscontacting, in particular also due to different coefficients of thermal expansion of the connector and circuit board.